Dredge the chicken breasts in the flour.,Heat the oil in a frying pan, and add the chicken breasts.,Cook until done, about 7 minutes each side (don't forget to flip it!).,______,Add the margerine to the pan and let it melt.,Add the sliced onion.,When fragrant and soft, add the tomatoes, and saute 3 minutes.,When the tomatoes are looking less than firm, add the pesto, cream or milk, and oregano, and mix together.,Let heat through.,This sauce goes very well over couscous too: place couscous on the plate, lay chicken over top, and then add the sauce.,Or you could add the chicken to the sauce before spooning onto the couscous.